Biology rarely re-invents the wheel. That is why proponents of the idea that presenilin (PS) and the proteolytic γ-secretases are one and the same will be pleased with a paper in tomorrow's Science by Bruno Martoglio and colleagues...

An article in the February 24 Nature Neuroscience online suggests that amyloid-β (Aβ), the peptide responsible for the intercellular plaques that appear in the brains of Alzheimer's patients, can freely diffuse through neural tissue, and that it plays a major role in the pathogenesis of the disease...